Basic puppet: Writing infrastructure configuration with an ENC, style, how-to?

Question

I barely know enough Puppet to ask this question.

I think I understand that the configuration for a particular node would consist of a collection of modules, with some node-specific glue. From the tutorials and documentation, it appears that the node-specific resources would be in a manifests/site.pp file, in node /nodename/ { } resources, with "includes" for the relevant classes, and resources to make node-specific configuration changes.

Now enter an External Node Classifier (ENC) such as theForeman.

From my reading of the ENC documentation, I COULD use node /nodename/ { } resources in a site.pp, but I can't declare any new resources. It's basically not recommended. The generated YAML is all just includes and variable settings.

So what does one do for configuration specific to a given node or a host group -- the wiring that integrates all your included classes?

Do you end up creating a class that's specific to the node? Where do you put that class, in a node-specific module? Or do you make a catch-all module for your site-specific configuration with classes that can be assigned to a specific node?

Answer 1

One approach to this is expressed in Designing Puppet – Roles and Profiles. The basic tenets are as follows:

• A node includes one role, and one only.
• A role includes one or more profiles to define the type of server
• A profile includes and manages modules to define a logical technical stack
• Modules manage resources
• Modules should only be responsible for managing aspects of the component they are written for

Answer 2

I am assuming you are telling Foreman to import from a puppet master, if so I would suggest setting up your puppet dir like this:

puppet
puppet/manifests
puppet/manifests/site.pp
puppet/manifests/nodes/default.pp
puppet/manifests/nodes/{server-type}.pp
...
puppet/modules
puppet/modules/{module1}
puppet/modules/{module1}/files
puppet/modules/{module1}/manefests
puppet/modules/{module1}/templates
...
etc

you would then include this line in the site.pp file:

import 'nodes/*'

Then, in default.pp create your base server:

node default {
    #this is where you put all of the puppet directives you want on every server.
    #for example if you wanted screen on all of your servers
    package{ "screen": ensure -> installed; }
}

Then in another file under nodes, say web.pp you could include that and then set the directives for all web servers like so:

node /^web0[1-9]\.example\.com$/ inherits default {
    #this will inherit all of the settings in the default node and then do anything else you add.
    #like installing nginx
    package { "nginx": ensure -> installed; }
}

You can even chain inherits like in this db.pp file:

node db inherits default {
    #install postgresql-9.3
    package { "postgresql-9.3": ensure -> installed; }
}

node /^db0[1-9]\.example\.com$/ inherits db {
    #This block can even be empty unless you need something here.
}